This invention relates to refrigeration systems and, more particularly, relates to purge systems for removing noncondensible gases and other contaminants from refrigeration systems.
Within refrigeration systems various noncondensible gases and other contaminants normally become mixed with refrigerant used in the refrigeration system and tend to collect at some point in the refrigeration system such as at the top of a condenser in a vapor compression refrigeration system. The presence of noncondensible gases and other contaminants in a refrigeration system reduces the efficiency of the refrigeration system since, for example, their presence necessitates higher condenser pressures with accompanying increases in power costs or in the amount of cooling fluid, such as relatively cold water, used to condense refrigerant in the condenser. The capacity of the refrigeration system is also reduced since the noncondensible gases displace refrigerant vapor flowing through the refrigeration system.
To overcome the foregoing described disadvantages, purging devices of various types may be used to remove or purge noncondensible gases and other contaminants from refrigeration systems. Such purging devices normally include a purge chamber for collecting the noncondensible gases, such as air, and for expelling them to the atmosphere. The gases which collect in the purge chamber also include water vapor and some refrigerant vapor. Usually a heat transfer coil is located within the purge chamber and is supplied with a cooling fluid, such as water or refrigerant. The heat transfer coil operates as a condensing coil to condense the refrigerant and water vapor to a liquid in the purge chamber. Then, these condensed liquid constituents, such as the refrigerant and the water, are removed from the purge chamber. Typically, the condensed liquid refrigerant is recirculated to the refrigeration system and the condensed water is expelled from the refrigeration system. The noncondensible gases are usually vented to the atmosphere by an automatic pump which operates in response to a pressure differential between the purge chamber and the condenser of the refrigeration system.
In purge systems of the type described above, if the purge pump operates excessively or malfunctions then undesirable amounts of refrigerant may be expelled to the environment. When using such purge systems, it is highly desirable to minimize the amounts of refrigerant expelled to the environment since refrigerant is expensive to replace in the refrigeration system and is an undesirable contaminant in the environment.